The long term objectives of this project are to develop and apply quantitative methods by which to measure and characterize blood transfusion practice in specific diagnoses and procedures; to open scientific communication about transfusion practice within and across institutions; and to develop simpler methods for estimating annual national blood collections and transfusions. The experimental design is based on the study and analysis of several unique sets of data. One set consists of abstracted patient data including ICD-9-CM diagnosis and procedure, DRG and red cell units transfused, from a constant set 100 of US hospitals for the years 1980,82,84,86, to which a new set of data will be added for the year 1989. A similar set of data will be gathered from 8 cooperating teaching hospitals over the first 4 years of the grant term; this set will include data for transfusions of all blood components, autologous units and factor preparations. A third data base contains the data for 4 US surveys conducted in 1982,84,86,87; and will be expanded to include 1990 and 92. Using these data, 4 main tasks will be addressed. A Pan-DRG red cell transfusion study will reveal red cell use across all DRGs and ICD-9-CM codes. Extensive efforts will be devoted to developing new methods to characterize transfusion practice. A series of studies will be devoted to characterizing transfusions of all blood components in a selected number of ICD-9-CM classes. The purpose of the fourth task is aimed at developing simpler and more rapid alternative methods for producing national estimates of transfusion activity; as part of this task,new surveys will be conducted for 1990 and 92. Among the questions to be studied are: Can we identify distinctive attributes of the patients who, though operated, did not require a transfusion or who require a large volume of blood? Are transfusions of non-red cell components related to use of red cells? Can transfusion frequency diagnosis for all blood products be used as a measure of transfusion practice? Do longitudinal comparisons of transfusions over the 9-year interval, 1980-1989, reveal significant trends? Is it possible to discriminate quantitatively between transfusion practices in different hospitals or set of hospitals, or at different times? What is the effect of autologous blood programs in transfusion practice? What is the contribution of comorbid conditions on red cell and component transfusion patterns.